Association Between Redlining and Spatial Access to Pharmacies

This cross-sectional study evaluates whether there is an association between historic redlining and living within 1 or 2 miles of a pharmacy.


Introduction
Historic redlining was a practice implemented in the 1930s by the Homeowners Loan Corporation that identified areas based on the population risk to default on mortgage. 1 Previous ecological studies have demonstrated that the detrimental effects of redlining on health outcomes persist in the present. 1 To our knowledge, no study has evaluated the association between redlining and spatial access to health care, including pharmacies. Pharmacy access is particularly relevant for equity in health care access because pharmacies reach individuals who do not have access to other health care settings. 2 We conducted a nationwide geographic information systems analysis to estimate the association between residence in a historically redlined neighborhood and spatial access to community pharmacies. The figure shows the odds ratio and marginal predicted probability of optimal pharmacy access, which was estimated by a regression model that regressed optimal spatial access to pharmacies against redlined neighborhoods, controlling for age, race and ethnicity, income, gender, and Area Deprivation Index (ADI). Figure also shows interaction between ADI and redlined neighborhood. Q indicates quartile.
We performed a multivariate logistic regression to evaluate the association between residence in a redlined area and spatial access to a pharmacy, controlling for age, sex, race and ethnicity, household income, and Area Deprivation Index (ADI). ADI is a measure of socioeconomic disadvantage and was operationalized as an indicator variable denoting residence in a block group within the fourth quartile of ADI (most deprived neighborhoods). 6 We conducted interaction analyses to test whether the association between residence in a redlined neighborhood differed by ADI. We conducted 2-sided t tests with a significance level of .05.

Results
In the sample of 13 009 569 synthetic individuals, 48.0% were women; 22.6% were Hispanic, 19.4% were non-Hispanic Black, and 45.3% were non-Hispanic White; and 86.2% were younger than 65 years. Overall, 85.4% of the sample lived within 1 mile of a community pharmacy and 98.7% within 2 miles (Table). Residence in a redlined census tract was associated with 9% decreased odds of pharmacy access within 1 mile (Figure, A). Residence in a deprived neighborhood (top quartile of ADI) was associated with 59% decreased odds of pharmacy access within 1 mile (probability of pharmacy access within 1 mile, 76% in ADI quartile 4 vs 88.6% in ADI quartiles 1-3).
The association of redlining on pharmacy access differed with ADI (P for interaction < .001). The consequences of redlining were particularly pronounced in most deprived neighborhoods, where redlining was associated with 35% and 51% decreased odds of living with 1 and 2 miles of a pharmacy, respectively.

Discussion
To our knowledge, our study is the first nationwide evaluation of the association between historical redlining and spatial access to health care. Our findings are limited by the sole estimation of pharmacy access based on driving distance, which does not account for diversity in modes of transportation. Our nationwide assessment of the association between historical redlining and spatial access to pharmacies provides additional evidence of the detrimental effects redlining continues to have on population health, particularly in socioeconomically deprived neighborhoods.
Our findings support the consideration of policies that prevent the closure and incentivize the opening of health care facilities, like community pharmacies, in historically redlined and deprived neighborhoods.